Safety device for hoists.



L. RIEFSTAHL.

SAFETY DEVICE FOR HOISTS. APPUCATION FILED JULY 20. I915.

1 21 6, 1 6E" Patented Feb. 13, 191?.

Inventor": Ludwig RieF'stahI, b5

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unrrn dhd ATENT LUDWIG RIEFSTAHL, OF VIENNA, AUSTRIA-HUNGARY, ASSIG-NOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SAFETY DEVICE FOR HOISTS.

Specification of Letters Patent.

Patented Feb. 13, 1917.

Application filed July 20, 1915. Seria1 No. 40,856.

To all whom it may concern:

Be it known that 1, LUDWIG RInrsTAHL, a citizen of Germany, residing at Gumpendorferstrasse 6, Vienna, Austria-Hungary, have invented certain new and useful Improvements in Safety Devices for l lolsts, of which the following is a specification.

This invention relates to the operation of hoisting mechanism or the like, and has for its object the provision of means whereby the hoisting apparatus is automatically brought to rest at the proper position without dangerous over travel in a simple, reliable and efficient manner.

My invention relates more specifically to the operation of hoists, winches or the like which are equipped with a safety brake employed, among other purposes, for preventing the cage from being lifted too high after passing the stopping or unloading pomt. Heretofore it has been customary to employ a safety device such, for instance, as a drop weight brake operated by a depth indicator so that when the cage reaches a predetermined point the safety device is operated by the depth indicator so as to stop the cage after the stopping point is passed. The space allowed between the upper landing of the cage and the upper drum or head sheath is not great. If, for instance, an operator should approach the upper landing at full speed, the operation of the safety dev ce might not be successful in stopplng the hoist before damage is done, although if the speed had been reduced the safety device would have performed its function properly. One of the objects of my invention is to provide means whereby the point of application of the safety brake with reference to the stopping point may be varied by the position of the controller so that if the controller is at high speed position the safety device will be applied morequickly than when it is in the low speed position. Other ob ects and purposes of my invention will appear 1n the course of the following speclfication, in which 1 have shown my invention embodied in concrete form for purposes of illustration.

In the accompanying drawing illustrating one form of my invention, Figure 1 represents somewhat diagrammatically a safety device operated by a depth indicator; Fig. 2 shows the controller with means attached thereto for varying the operation of the safety device; and Fig. 3 is a general view of my device applied to a hoist.

Referring first to Fig. 3, it will be seen that I have shown in a conventional way the outline of a hoist comprising a hoisting drum 10, upp r drum or head sheave 11, and cage 12. I have shown the hoist operated by an electric motor 13 which drives the drum 10 in the well known manner. Associated with the hoist is a depth indicator which is merely shown in outline as c01nprising a nut 1a which is moved up and down by means of a screw thread 15 arranged to engage the stop 16 at the upper limit of its movement. it will be seen that the stop 16 is mounted on a rod 1? which is arranged to be shifted longitudinally when the stop 16 is engaged by the nut 14: at the upper limit of its travel. At the lower end of the rod 17 is an arm 18 which when lifted is adapted to engage the arm of latch 19 pivoted at 20.- This latch supports the safety brake 21. When therefore the hoist reaches a predetermined position, as indicated by the position of the nut 1 1 of the depth indicator, the arm 18 will be lifted and the safety brake 21 applied.

Whether the safety brake will stop the hoist in time to prevent damage will depend upon the speed at which the hoist is run ning when the brake is applied, and upon the point of application of the brake with reference to the stopping point. In order to automatically change the point of application of the brake with reference to the stopping point in accordance with the speed, 1 provide means whereby the position of the controller varies the point at which the nut 1 1 of the depth indicator applies the brake. In the particular arrangement which 1 have shown I employ a suitably shaped member 22 which is interposed between the arm 18 and the latch 19. This member is tapered, as shown in Fig. 2, so as to give different spacing distances between the arm and the latch, depending upon the position of the controller arm 23. As shown, the member 22 is interlocked with the controller by means of an arm 24 on the controller shaft which engages in a slot in the member 22. This construction is intended to be merely typical as illustrating one way of accomplishing my result, but it is obvious, of course, that many other mechanisms may be employed for accomplishing this result without departing from the spirit of my in vention.

It will now be seen that as the hoist approaches the upper limit of its travel the nut 14: of the depth indicator will engage the arm 16 and apply the safety brake 21. If the controller 25 is thrown to the high speed position the spacing member 22 will be in a position so as to engage the latch and apply the safety weight earlier in the movement of the depth indicator than would be the case if the controller were in the low speed position. By properly forming the member 22 or by the use of suitable or equivalent mechanism, the brake will be applied at the proper point with reference to the stopping position for all positions of the controller. IVhile I have described my invention as embodied in concrete form and as operating in a specific manner for purposes of illustration, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination with a hoist or the like, an electric motor for operating the same, a controller for said motor, a stopping device operated at predetermined positions of the hoist cage and means whereby the operation of the stopping device is varied in accordance with the position of the controller.

2. In combination with a hoist or the like, a manual controller therefor, a stopping device operated at predetermined positions of the hoist cage, and means whereby the operation of stopping the hoist is varied in accordance with the position of the controller.

3. In combination with a hoist or the like, a manual controller therefor, a safety brake for stopping the same operated at predeter- Copies of this patent may be obtained for five cents each, by addressing the mined positions of the cage, and means whereby the operation of said brake is varied in accordance with the position of the controller.

4. In combination with a hoist or the like, an electric motor for operating the same, a controller for said motor, a safety brake operated at predetermined positions of the hoist cage, and means whereby the point of application of the brake with reference to the stopping point is varied in accordance with the position of the controller.

5. In combination with a hoist or the like, an electric motor for operating the same, a controller for said motor, a safety brake, a depth indicator for operating the brake at a predetermined position of the hoist cage, and means whereby the point at which the depth indicator operates the brake is varied in accordance with the position of the controller.

6. A hoisting device having a cage and a motor for operating the same, a manually operated controller therefor, a safety brake, means for applying said brake at a limiting position of said cage and a member operated by said controller for varying the tripping point of said brake applying means with respect to the limiting position of said cage.

7 The combination of a cage or car with a hoisting drum, an electric motor operatgigl the same, a controller therefor, a safety ra re, adapted to apply said brake at a limiting position of said cage and a controller moved member for varying the tripping point of the brake applying means with respect to the depth gage whereby excessive motor speeds are compensated therefor.

In witness whereof, I have hereunto set my hand this 22nd day of May, 1915.

LUDIVIG RIEFSTAI-IL. Witnesses:

JULIUS Rozrnn, WVILHELM KRUTZFELDT.

Commissioner of Patents,

Washington, D. 0.

means comprising a depth gage 

